The invention refers to a semiconductor component, in particular a thyristor, having emitter short-circuits in the cathode space.
The employment of emitter short-circuits is known in the case of thyristors for prevention of undesirable ignition in the case of a steep rise in the anode voltage (dv/dt -- ignition). It is moreover known that, during the load-like critical phase directly after ignition has resulted, these emitter short-circuits inhibit spreading of the ignition spot (H. Yamasaki -- "Experimental Observation of the Plasma Propagation in a Thyristor", appearing soon in IEEE Transactions on Electronic Devices).
There also exists a first proposal according to which, in spite of the employment of emitter short circuits, spreading of the ignition does not get inhibited (Swiss Pat. No. 552,283). In accordance with this proposal a circular emitter short-circuit is provided around the ignition electrode (gate). This short-circuit ring certainly confers potential advantages, yet in the case of employment of the technology in use at present, it can lead to intolerably high ignition currents.
As was further observed, in the case of a steep rise of current in components fabricated from a homogeneous material or crystal structure, current paths form in special crystal directions (P. Voss -- "Observation of the Initial Phases of Thyristor Turn-On", Solid State Electronics, 17, pages 1087-1090, 1974). The occurrence of local momentarily strongly heated points has also been detected. Such local heating, however, shows a serious defect; and, whenever it occurs, safe, reliable operation of the component is open to question.